TAL effector specificity for base 0 of the DNA target is altered in a complex, effector- and assay-dependent manner by substitutions for the tryptophan in cryptic repeat -1.

ABSTRACT: TAL effectors are re-targetable transcription factors used for tailored gene regulation and, as TAL effector-nuclease fusions (TALENs), for genome engineering. Their hallmark feature is a customizable central string of polymorphic amino acid repeats that interact one-to-one with individual DNA bases to specify the target. Sequences targeted by TAL effector repeats in nature are nearly all directly preceded by a thymine (T) that is required for maximal activity, and target sites for custom TAL effector constructs have typically been selected with this constraint. Multiple crystal structures suggest that this requirement for T at base 0 is encoded by a tryptophan residue (W232) in a cryptic repeat N-terminal to the central repeats that exhibits energetically favorable van der Waals contacts

SUBMITTER: Doyle EL 

PROVIDER: S-EPMC3849474 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature